NMR techniques have grown extensively over the past forty years, most notably in the medical instrumentation areas where in vivo examination of various parts of the human body can be seen, and in clinical research laboratory uses. In addition there has been some use and interest in the application of these techniques to industrial instrumentation and control tasks. The present invention enables effective utilization (technically and economically) of pulsed NMR techniques in industrial areas to replace or complement existing optical and radiant energy-based instrumentation.
Pulsed NMR spectroscopy is described in our above-cited patent. This technique uses a burst or pulse which is designed to excite the nuclei of a particular nuclear species of a sample being measured (the protons, or the like, of such sample having first been precessed in an essentially static magnetic field); in other words the precession is modified by the pulse. After the application of the pulse there occurs a free induction decay (FID) of the magnetization associated with the excited nuclei. Traditional Fourier Transform analysis generates a frequency domain spectrum which can be used to advantage in studying the nuclei of interest. The duration of the pulses, the time between the pulses, the pulse phase angle and the composition of the sample are parameters which affect the sensitivity of this technique. These frequency domain techniques are not easily useable in industrial applications, especially on-line applications.
An object of this invention is an improved measurement system which leads to accurate, fast determination of the types and quantity of the nuclear species of interest.
A further object of this invention is its application to the industrial, on-line problems of measuring and calibrating the controlling processes per se.
Another object of this invention is to utilize time domain analysis in achieving such system.
The principal variables of interest are polymer crystallinity, tacticity and the molecular structure of polypropylene. But other parameters may be measured. It is an object of this invention to accommodate a variety of such measuring tasks.
Another object is to accommodate the dynamics of industrial on-line applications including variations of density, temperature, packing and size factors, friction and static electricity, vibrations and frequent, repetitive, cyclic and non-cyclic measurements.
A further object of the invention is to integrate all the features of accurate, fast determination of the types and quantity of the polymer molecular structure of interest, the use of time domain analysis in such a system, its application to the industrial, on-line problems of monitoring and controlling processes accommodating the dynamics of industrial on-line applications including variations of density, temperature, packing and size factors, friction and static electricity, vibration and frequent, repetitive, cyclic and non-cyclic measurements.
A further object of the invention is to use such magnetic resonance techniques in polypropylene analysis, including crystallinity, tacticity and density, all with enhanced accuracy and reliability of data obtained and while achieving the necessary practical economies.
A further object of the present invention is to extend those achievements further in relation to industrial on-line processing, and the like of NMR-active materials and more particularly to polypropylene wherein the tacticity of the material, and the concurrent molecular structure is determined on-line.